Semiquantal modeling of thermal vibrational relaxation of diatomic molecules

Vibrationally excited molecules play an important role in the spectroscopy, energetics, and chemical behavior of a wide range of gaseous systems of scientific and applied interest. Unfortunately, many desired collisional relaxation rates have not yet been experimentally measured, and current theoretical methods are often inadequate or too cumbersome for practical application. We report a semiquantal two-parameter scaling method for predicting relaxation rates that is very simple to employ, and impressively fits the temperature and vibrational dependencies of quantum mechanical and experimental collisional relaxation rates for several diatomic molecules (e.g., N2, HF, OH, NO) over many orders of magnitude.